Processing of smoking tobacco



United States Patent 3,316,919 PROCESSING OF SMOKING TOBACCO SydneyJames Green, Portswood, and William Brian Fordyce, Romsey, England,assignors to Brown and Williamson Tobacco Corporation, Louisville, Ky.,a

corporation of Delaware No Drawing. Filed Apr. 21, 1964, Ser. No.361,578 Claims priori application Great Britain, Apr. 29, 1963,

16,832/ 63 8 Claims. (Cl. 131--143) This invention concerns improvementsrelating to the treatment or processing of tobacco. An object of theinvention is to provide a simple and practicable means by which thearoma and smoke flavour of a smoking tobacco can be improved ormodified. Such improvement may be desirable because the tobacco is of alow grade or suflers losses of aroma or flavour constituents in thecourse of its preparation.

Some of the more volatile aroma or flavour constitucuts of tobacco arein fact lost during conventional processing of leaf-tobacco into a formsuitable for smoking purposes. Attempts have been made to avoid theselosses, for example by operating at low temperatures duringconditioning, blending and cutting operations, but these have been onlypartially successful. Attempts to recover the aromatic substances fromthe atmosphere have also proved diflicult or impracticable. The presentinvention seeks, inter alia, to provide means by which volatile aromaticsubstances in tobacco can be extracted and used to make up losses fromtobacco processed in the usual way.

According to the invention, tobacco, preferably in a ground state, isextracted with a chilled solvent such as ice-cold water and the liquidobtained by the extraction is solidified and freeze-dried. Preferably, afilter is employed to retain the tobacco during the extraction. Thus,

obviate substantially decomposition of the more unstable aroma andflavour constituents. For example, a rate of about 3-6 ml./minute mayadvantageously be used. The eflluent liquid may be collected in areceiver maintained at a temperature substantially below 0 C., so thatit freezes almost immediately on contact with the walls. On completionof the extraction, the solidified liquid is freeze-dried, yielding apale-brown product of high aromaticity.

This product, in the form of a fine powder, can be used to impartflavour and aroma to conventionally prepared smoking tobacco either byadding up to, say, 10%, but of the powder to the tobacco,

reconstituted tobacco products.

By such methods, which can be easily applied in practice, the impactaroma and smoke flavour of cigarettes can be appreciably changed byadding to the tobacco a freeze-dried extract from an aromatic orcharacterful tobocco. This may be done (a) to modify low grade flavourmay be available from waste tobacco sources. In all cases, theflavouring tobacco may be a relatively cheap material.

Examples of ways of carrying the invention into etfect will now be morefully described:

Example 1 (a) parts of aromatic fire-cured tobacco were reduced to /8inch diameter particles and extracted with chilled, preferably ice-cold,water using 6 parts by weight of water to each part of tobacco. Theextraction was carried out at a rate of 5 mL/minu'te by percolation ofthe ice-cold water through a bed of supported by a filter screen.

In the extraction, it is important that the period of contact betweenthe chilled water andthe tobacco should be substantially the sameregardless of the quantity of tobacco. This involves co-relating thetotal flowrate to the area and porosity of the filter and the depth ofthe bed of tobacco. A flow-rate of .3-6 mL/min. may suitably be employedfor a 2 inch depth of bed supported by a 4 inch diameter screenwith arange of maximum pore diameters of 15-40 microns (i.e. Grade No. 3 ofBritish Standards Specification 1752 Laboratory Sintered or FrittedFilters). Variations of the three parameters to give the requiredcontact period for different quantities of tobacco with diflerent sizesof equipment can be calculated.

The efiluent liquid from the extraction was immediately frozen by beingcooled to about 50 C., at which tem perature substantially all thematerial extracted remains involatile and chemically inert. The waterwas then removed by freeze-drying carried out with the frozen efiluentat -50 C., .a drying chamber temperature of 28 to 40 C., preferably 35C., and a pressure decrease until the temperature of the residueattained the temperature of the drying chamber. At this temperature, thedried residue was substantially stable chemically. 19 parts of a fine,pale-brown, powder were produced.

The two temperatures, 50 C. and +35 C., were chosen to ensure not onlythat the extracted material remained virtually constant in its chemicalcomposition during processing, but also to give a reasonable value forthe water-vapour pressure over the icy mixture during processing and toavoid an unduly long processing time.

Pulverisation of the product of the freeze-drying process under theconditions specified was unnecessary, but if the frozen effluent had ahigher concentration of extracted material, a highly friable flake maybe produced which would require pulverisation.

(b) The powder produced in the above-described manner was dusted evenlyonto a blend of cut tobacco rag of high quality to give an addition of5% by weight of the powder to the original weight of the cut tobacco.The material so obtained was made into cigarettes and was smoked by apanel of smokers in comparison with cigarettes made from untreatedsimilar tobacco. A majority of the panel noticed a marked enhancement ofthe flavour characteristics of the smoke from the treated cigarettes.

Example 2 Powder produced as in Example 1(a) was dusted evenly onto ablend of cut tobacco rag of low quality to give an addition of 5% byweight of the powder to the original weight of the cut tobacco.Cigarettes made from this material were smoked by a panel of smokers incomparison with cigarettes made from untreated simi- A markedimprovement and enhancement from the treated cigarettes r tobacco.

the flavour of the smoke as noticed.

Example 3 an aromatic Burley tobacco were (a) 100 part of 21 parts of afine Example 4 Using the powder produced in accordance with Examle 3(a),the procedure described in Example 2 was caried out. A panel of smokersnoticed a marked improveient of the flavour of the smoke from thecigarettes nade from the treated tobacco.

We claim:

1. A method of treating tobacco comprising preparng a bed of groundtobacco disposed on a filtering means laving a porosity such that asolvent passing through the 16d is controlled at a sufiicient rate so asto obviate subitantially decomposition of the more unstable tobaccoiroma and flavor constituents contained in the liquor; :xtracting theground tobacco with an ice-cold solvent 9y percolation of the solventthrough the bed of tobacco; rapidly freezing the liquor by subjectingthe liquor to a temperature substantially below the freezing point ofthe solvent so that all of the material extracted remains substantiallyinvolatile and chemically inert and then freeze drying the frozen liquorby subjecting the frozen liquor to reduced pressures while maintainingthe liquor in a frozen state until the flavor and aroma constituentsextracted from the tobacco are free of solvent.

2. A method as claimed in claim 1, wherein the solvent is ice-coldwater.

3. A method as claimed in claim 1, wherein the tobacco is reduced toabout Ms inch particle size and is extracted with ice-cold water, using6 parts by weight of water to each part of tobacco, by percolating thewater through the tobacco, supported as a bed on a filter screen, at arate of about 5 ml./ per minute, the percolated liquor being rapidlyfrozen and the water removed by freeze drying.

4. A method of treating tobacco as set forth in claim 1 wherein thefreeze dried flavor and aroma constituents are added to a smokingtobacco in a proportion up to 10% of the freeze dried material based onthe weight of the smoking tobacco.

5. A method of preparing an improved flavor and aroma tobacco smokingproduct comprising preparing a bed of ground tobacco disposed on afiltering means having a porosity such that a solvent passing throughthe bed is controlled at a sufficient rate so as to obviatesubstantially decomposition of the more unstable tobacco aroma andflavor constituents contained in the liquor; extracting the groundtobacco with an ice-cold solvent by percolation of the solvent throughthe bed of tobacco; rapidly freezing the liquor by subjecting the liquorto a temperature substantially below the freezing point of the solventso that all of the material extracted remains substantially involatileand chemically inert and then freeze drying the frozen liquor bysubjecting the frozen liquor to reduce pressures while maintaining theliquor in a frozen state until the flavor and aroma constituentsextracted from the tobacco are free of solvent, and then adding thefreeze dried flavor and aroma constituents to smoking tobacco in aproportion up to 10% by weight of the aroma material based on the weightof smoking tobacco and then forming a smoking tobacco product.

6. A method as claimed in claim 5, wherein the said product, in the formof a fine powder, is dusted upon the said smoking tobacco.

7. A method as claimed in claim 5, wherein the said product is added ina proportion of about 5% of the said smoking tobacco.

8. A smoking tobacco product made by the method of claim 5.

References Cited by the Examiner UNITED STATES PATENTS 720,830 2/1903Marsden 131143 1,016,844 2/ 1912 Moonelis 131143 X 2,783,149 2/ 1957Epstein 99-7l FOREIGN PATENTS 832,991 4/ 1960 Great Britain.

910,451 11/1962 Great Britain.

SAMUEL KOREN, Primary Examiner.

MELVIN D. REIN, Examiner.

1. A METHOD OF TREATING TOBACCO COMPRISING PREPARING A BED OF GROUNDTOBACCO DISPOSED ON A FILTERING MEANS HAVING A POROSITY SUCH THAT ASOLVENT PASSING THROUGH THE BED IS CONTROLLED AT A SUFFICIENT RATE SO ASTO OBVIATE SUBSTANTIALLY DECOMPOSITION OF THE MORE UNSTABLE TOBACCOAROMA AND FLAVOR CONSTITUENTS CONTAINED IN THE LIQUOR; EXTRACTING THEGROUND TOBACCO WITH AN ICE-COLD SOLVENT BY PERCOLATION OF THE SOLVENTTHROUGH THE BED OF TOBACCO; RAPIDLY FREEZING THE LIQUOR BY SUBJECTINGTHE LIQUOR TO A TEMPERATURE SUBSTANTIALLY BELOW THE FREEZING POINT OFTHE SOLVENT SO THAT ALL THE MATERIAL EXTRACTED REMAINS SUBSTANTIALLYINVOLATILE AND CHEMICALLY INERT AND THEN FREEZE DRYING THE FROZEN LIQUORBY SUBJECTING THE FROZEN LIQUOR TO REDUCED PRESSURES WHILE MAINTAININGTHE LIQUOR IN A FROZEN STATE UNTIL THE FLAVOR AND AROMA CONSTITUENTSEXTRACTED FROM THE TOBACCO ARE FREE OF SOLVENT.